Mode of manufacturing a new form of synthetic indigo.



" nn'rr i erases ALBRECHT SCHMIDT AND ADOLF STEINDORFE, F HGCEST-DN-THE-WIAIN, GERMANY 'ASSIGNORS TO FARBWERKE VORIVI. MEIS'IER LUCIUS & BRiiNING, OF HGCHST-GN- THE-MAIN, GERMANY, A CORPORATIQN 0F GERMANY.-

MODE OF MANUFACTURING A. NEW FORM OF SYNTHETIC IHZDIGQ.

No Drawing.

Specification of Letters Patent.

Application filed August 23, 1911. Serial Ho. 645,810.

' Patented Apr. 1, 1013.

To aZZ whom it may concern:

Be it known that we, ALBRECHT ScHMin'r, Ph. D., chemist, and AnoLF STEINDORFF, Ph. D., chemist, citizens of the Empire of Germany, residing at I-Idchston-the-Main, Germany, have invented certain new and useful Improvements in the Mode of Wannfacturing a New Form of Synthetic Indigo, of which the following is a specification.

In U. S. Patent applications Ser. No. 576,703, filed 11th August 1910, and Ser. No. 577,200, filed 15th August 1910, it has been described that indigo can be produced in an extremely finely subdivided condition by causing itto form in presence of an aromatic sulfonic or carboxylic acid, for instance from its leuco compounds by the action of the atmospheric air or any other oxidizing agent, or from its mineral-acid salts or solutions by dissociation with water. Now we have furthermore found, that also -;1romatic phenols have a like action. Thus,

a finely-subdivided indigo can for instance be obtained by blowing solutions of indigo lcuco compounds with air, or by dissociating indigo salts by means of water in pres-.

ence of phenol, cresol (particularly the technical cresol mixture), resorcin, guaiacol, pyrcgallol, 1. l-dioxynaphthalene-mono-benzylether, oxyanthraquinonc, a-anthrol, etc.

Example lzflOO parts by weight of an indoxyl melt of strength are dissolved in 1000 parts of water with addition of 5 parts of resorcin, and this solution is then treated with air until the indigo precipiwhile well stirring. The separated finely divided indigo is filtered and Washed with water.

@Havmg now described our invent on,

what we claim is:

1. The process of manufacturing a new form of synthetic indigo, which consists in subjecting indol derivatives which are closely related to indigo and capable of directly yielding indigo to indigo-producing conditionsin presence of a phenol.

2. The process of manufacturing a new form of synthetic indigo, which consists in subjecting indigo salts to indigo-producing conditions in presence of a phenol.

3. The process of manufacturing a new form of synthetic indigo, which consists in subjecting leuco-indigo salts to oxidation in presence of a phenol.

In testimony whereof, we atlix our signatures 1n presence of two Witnesses.

ALBRECHT SCHMIDT. ADOLF STEINDORFF.

Witnesses:

JEAN Gnnnn, CARL Gnnnn. 

